We wish to approach the direct analysis of the human genome in terms of comparisons between DNA sequences of test and reference sources. Our immediate concern is with the detection, resolution, and quantitation of restriction enzyme fragments from eukaryotic DNA. We hope to detect the presence, absence, substitution, or heterozygosity of specific fragments by survey procedures which will examine all or a large part of the genomes. Our techniques are based largely on the use of sequence-dependent physical properties of DNA fragments to determine their mobility or position in two-dimensional gel electrophoresis, coupled with other procedures based on hybridization capability, or protein-binding specificity, molecular size to select defined subsets of the fragment population for study. We will refine a powerful new method of electrophoretic separation based on position-specific change of fragment mobility in gels, and explore further means for introducing different, sequence-dependent discriminations. We will test DNA of mutants in yeast affecting restriction enzyme fragmentation at the cytochrome c gene. In mice we will be concerned with a series of deletion alleles at the c (albino) locus of chromosome 7. We hope to achieve rough mapping of fragments with respect to the recognized markers at the locus and to examine some properties of the sequences with respect to their biological function.